Neutrino Core

RiptOPL can hand any individual game to an external Neutrino ELF instead of OPL's built-in EE core. The choice is made per game, leaving other titles on the default OPL core untouched. This is useful for titles that boot more reliably under Neutrino, or when you want fine-grained control over Neutrino's own launch flags.

Neutrino is created by rickgaiser — a "Small, Fast and Modular PS2 Device Emulator". The release package bundles the official latest build as a ready-to-use neutrino/ folder under its AFL-3.0 licence; see Credits for the full attribution. Report launching problems to us and genuine Neutrino bugs upstream.

1. Install Neutrino

The release package includes a complete neutrino/ folder: copy the whole folder to a location RiptOPL can keep available through the handoff. On ordinary non-MMCE setups, mc0:/neutrino/ or mc1:/neutrino/ is supported. A memory card is the last automatic location OPL looks, not the first.

The full lookup order is:

A miss on the device you picked falls through to the automatic tiers. The exception is Game's Device, which only looks on the game's own device and reports "not found" instead of falling back.

The internal APA HDD is also searched, through the OPL data partition OPL has already mounted — the same partition NHDDL resolves for its own hdd0:/<OPL partition>/neutrino/neutrino.elf rule (read from hdd0:__common/OPL/conf_hdd.cfg, with +OPL or __common/OPL as fallbacks). In practice that means one of these two layouts, with nothing to configure:

The APA HDD must be started for this to resolve — nothing is mounted to read otherwise — but the game itself may live anywhere: a USB or MMCE game can boot from an APA-hosted Neutrino, and OPL keeps that partition mounted across the handoff. An install on a partition that is not the OPL data home cannot be reached; move it, or use another device.

If none of those paths exist when you launch a game set to the Neutrino core, OPL shows a warning and falls back to the <OPL> core for that launch only.

Custom Neutrino ELF path

You can override the automatic lookup with the neutrino_path key in settings_riptopl.cfg; there is no menu row for it. In Auto, a valid custom path is checked before the active game device. Memory Card explicitly tries mc0:/mc1: first, while Game's Device ignores the custom path and searches only the active game's own device.

Network boot exception

The UDPBD / UDPFS feature ships its own bundled Neutrino — a drag-and-drop neutrino/ folder (neutrino.elf plus config/ and modules/) in the release zip, pre-populated with the UDPFS config. Per-game Neutrino use still needs you to supply neutrino.elf at the paths above.

2. Pick the core per game

Where Neutrino works

Unsupported sources fall back to the <OPL> core automatically with an on-screen warning. No manual intervention is needed — OPL detects the format and adjusts.

3. Neutrino Device picker

Under Settings → Game Launching → Neutrino Defaults → Default Device, the current picker intentionally exposes only three policies. Device-specific entries such as USB, MX4SIO, MMCE, exFAT HDD, APA HDD and iLink are not user-facing choices in current builds.

Available choices:

• Auto — checks a valid custom neutrino_path first, then the active game's prefix and bare device root, then the mounted APA HDD OPL data home, then the mc0:/mc1: candidates (default).
• Memory Card — tries mc0:/mc1: first; if they miss, the normal Auto fallback tiers are still available. MMCE users who need GameID card switching should not use an mcN:-hosted Neutrino on that same slot.
• Game's Device — searches only the active game's own device: its configured games-prefix path first, then the bare device root. There is no custom-path, APA-HDD or memory-card fallback; a miss shows "not found" and aborts the Neutrino handoff.

The active-device probe accepts the normal NEUTRINO/neutrino.elf / neutrino/neutrino.elf case variants. For MMCE this means, for example, mmce0:/OPL/neutrino/neutrino.elf when OPL is the Prefix Path, then mmce0:/neutrino/neutrino.elf at the bare root. The APA HDD remains a special Auto fallback through the already-mounted OPL data partition (see §1).

4. Launch arguments

OPL always builds the mandatory Neutrino arguments automatically from the game and its settings — most of which you never type yourself (-dbc, -logo and -gsm are the three exceptions: forward one yourself and OPL drops its own copy — see the callout at the end of this section, and §5):

Global and per-game extra args

On top of the auto-built arguments you can pass extra Neutrino flags in two places. Both sets are appended after the auto-built arguments; global first, then per-game, so a game can extend or override the global defaults.

• Global (every Neutrino launch): Settings → Game Launching → Neutrino Advanced Arguments — config key neutrino_args in settings_riptopl.cfg.
• Per game (one title only): Triangle → Game Settings → Neutrino Launch Args — config key $NeutrinoArgs in the game's .cfg.

Arguments are space-separated. Example:

-mt=dvd -gsm=1

Structured Neutrino Args sub-screen

Both the global entry (Settings → Game Launching → Neutrino Advanced Arguments) and the per-game field (Triangle → Game Settings → Neutrino Launch Args) are buttons that open the same companion sub-screen. It breaks the argument string into named fields — Quick Boot (-qb), Debug Colors (-dbc), PS2 Logo (-logo), Working Dir (-cwd), Config (-cfg), Boot ELF (-elf), ATA0 Image (-ata0), ATA0 ID (-ata0id), ATA1 Image (-ata1), plus a free-form Extra field — reassembles them in a valid canonical order with --b kept last, and writes the result back as a single flat string: the global into neutrino_args, the per-game value into $NeutrinoArgs (each game edited independently).

The canonical reassembly order is: -qb → -dbc → -logo → -cwd → -cfg → -elf → -ata0 → -ata0id → -ata1 → Extra. The Extra slot also collects any flags the parser does not recognise, preserving them verbatim. --b and everything following it is always kept at the tail (those tokens are arguments forwarded to the booted ELF, not to Neutrino itself).

5. Per-game Neutrino Video (-gsm)

When a game's Loader Core is set to Neutrino, a Neutrino Video picker appears in Game Settings. This is the Neutrino-side stand-in for the OPL GSM panel (which is an OPL-core-only feature and is greyed under Neutrino). The picker maps to Neutrino's -gsm flag:

Global default: the same picker also exists in Settings (with its GSM-comp half). Games whose per-game picker is “Default” follow it — so one global change forces e.g. -gsm=1080ix3 for every Neutrino game. An explicit per-game value — including Off — overrides the global.

The picker is the default source for -gsm. If you manually type -gsm=<value> into the Neutrino Launch Args field, that value wins — OPL emits only one -gsm argument, because Neutrino aborts on a duplicate or malformed value.

Mode 7 — fix IOP buffer overrun (-gc=7)

The compat modes list contains a Neutrino-only entry: Mode 7. This maps to -gc=7 and targets a small class of games that overrun an IOP buffer during loading. It is greyed out when the Loader Core is set to <OPL> (the inverse of Modes 4 and 6, which are greyed under Neutrino). Enable it in Game Settings when the game's core is Neutrino.

6. Core-aware per-game settings

The per-game settings screen adapts to the Loader Core chosen for each title, so you only see controls the selected core actually honors.

When Loader Core = Neutrino

• Neutrino Launch Args and Neutrino Video picker are active and editable.
• Compat Modes 4 (Skip Videos) and 6 (Disable IGR) are greyed — these are OPL ee-core features with no Neutrino equivalent. OPL never forwards them.
• Mode 7 is available (Neutrino-only; see above).
• Download Defaults is greyed — it pulls OPL bitmask data that does not map to -gc.
• The Configure GSM, Cheat Settings, Controller Emulation and OSD Settings screens show a "not used with the Neutrino core" message instead of dead controls. Use the Neutrino Video picker for video forcing.
• VMC and the rest of Game Settings remain fully available — VMC is passed to Neutrino as -mc0/-mc1 arguments on BDM devices (USB/iLink/MX4SIO/exFAT HDD/UDPBD), MMCE and UDPFS. The one exception is APA HDD: Neutrino has no APA/pfs backing store to open the .bin from, so the game boots without the VMC and OPL shows a warning (the OPL core honors the same card normally). See VMC with the Neutrino core.
• UDPBD / UDPFS games have no OPL core backend, so the Loader Core selector is locked to Neutrino for them and cannot be changed.

When Loader Core = <OPL>

The screen is unchanged from classic OPL. The Neutrino Launch Args field and Neutrino Video picker are greyed (they are never read on the OPL path). Mode 7 is greyed. Modes 4 and 6 are available as usual.

7. Network boot — UDPBD / UDPFS

UDPBD and UDPFS stream games from a PC over the LAN as network block devices. The block protocols (UDPBD and UDPFS-Image) share the BDM block tab — labelled UDPBD Games or UDPFSBD Games depending on which one is active — while UDPFS-Files is a separate filesystem device with its own UDPFS Games tab. Only one can be active per boot anyway (a single NIC), so the two never appear side by side. Either list carries covers and per-game settings. Because there is no OPL cdvdman backend for network block devices, these games always and only launch via Neutrino — OPL forces the Neutrino core automatically, and if neutrino.elf is missing it warns and returns to the menu (there is no <OPL> fallback).

Full setup, server instructions, and the UDPBD vs UDPFS protocol comparison are on the Network Boot page.